I was interested in putting the Wizard's Cottage on the island in a sort of "survivalist cabin" concept I had (small unassuming structures on the surface with a huge underground "bunker" connecting them. Liked the fencing which went with it. Not sure if it will bait-and-switch with the island default though. :/

Also I'm discovering that multistory renovations are VERY expensive. Hope to transplant one of my home designs to a new (big) plot before adding the planned second floor.